Interspecies sex doesn't always result in offspring that are infertile, like a mule. A fruit bat found in the Lesser Antilles of the Caribbean, Artibeus schwartzi, is a hybrid that has descended from three different species.

Peter Larsen from Texas Tech University confirmed the bat’s unique ancestry by sequencing DNA from 237 individuals belonging to the seven fruit bat species of the Lesser Antilles. He found that A.schwartzi’s main genome is a cross between those of two other fruit bats, A. jamaicensis and A. planirostris, with a tiny minority of sequences that don’t match either genome.

Complicating matters, animal cells also have a separate smaller genome, housed in energy-providing structures called mitochondria. But A.schwartzi’s mitochondrial genome doesn’t resemble that of either of the two species that gave rise to it. These accessory genes must have come from yet another source – a third species of fruit bat that has either since gone extinct or that hasn’t been discovered yet.

Hybrid species that came from a mashup of two other species are rare enough, but three is very rare indeed. Link